Backlight unit and liquid crystal display using the same comprising first and second light guide plate arrays connected to and independently controlled by first and second light array driving parts respectively

Abstract

A backlight unit capable of improving contrast properties by implementing a local dimming method while making the backlight unit slim, and a liquid crystal display using the same are provided. The backlight unit includes a first light guide plate array including a plurality of first light guide plates arranged in parallel in a first direction to define a first light guide channels; a second light guide plate array including a plurality of second light guide plates arranged in parallel in a second direction intersected with the first direction to a second light guide channels; a first light array arranged near at least one end of the first light guide plate array to illuminate light to the at least one end of the first light guide plate array; and a second light array arranged near at least one end of the second light guide plate array to illuminate light to the at least one end of the second light guide plate array.

What is claimed is: 
     
       1. A backlight unit comprising:
 a first light guide plate array including a plurality of first light guide plates arranged in parallel in a first direction to define a plurality of first light guide channels; 
 a second light guide plate array including a plurality of second light guide plates arranged in parallel in a second direction intersected with the first direction to define a plurality of second light guide channels, the second light guide plate array being disposed under the first light guide plate array, wherein the first light guide plate array and the second light guide plate array define a matrix of blocks such that a luminance of each block is the sum of the luminance of the first and second light guide channels at each block; 
 a first light array arranged near at least one end of the first light guide plate array to illuminate light to the at least one end of the first light guide plate array; 
 a second light array arranged near at least one end of the second light guide plate array to illuminate light to the at least one end of the second light guide plate array; 
 a first light array driving part independently controlling an amount of emitting light of each light source in the first light array and adjusting the current supplied to a light source of the first light array depending on a local dimming signal supplied directly from a picture analyzing part; and 
 a second array driving part independently controlling an amount of emitting light of each light source in the second light array and adjusting the current supplied to a light source of the second light array depending on a local dimming signal supplied directly from the picture analyzing part, wherein the picture analyzing part generates the local dimming signal for adjusting the current supplied to the first and second light arrays with reference to the luminance analyzed for each block to control the first and second light array driving parts, 
 wherein the first light array driving part is disposed along the first light array and the second light array driving part is disposed along the second light array, the first light array driving part not directly connected to the second light array driving part, 
 wherein a long edge of the first light guide plate extends beyond or is shorter than a long edge of the second light guide plate in a first direction along a plane of the first and second light guide plates, 
 wherein a short edge of the second light guide plate extends beyond or is shorter than a short edge of the first light guide plate in a second direction along the plane of the first and second light guide plates, the first and second directions being perpendicular to each other. 
 
     
     
       2. The backlight unit of  claim 1 , wherein surface light illuminated from the first and the second light guide plates is divided into a plurality of blocks formed by the intersection of the first light guide channels and the second light guide channels. 
     
     
       3. The backlight unit of  claim 1 , wherein the first light array includes a plurality of first light sources arranged to correspond to the one ends of the plurality of first light guide plates, and a plurality of second light sources arranged to correspond to the other ends of the first light guide plates, and
 the second light array includes a plurality of third light sources arranged to correspond to the one ends of the plurality of second light guide plates, and a plurality of fourth light sources arranged to correspond to the other ends of the second light guide plates. 
 
     
     
       4. The backlight unit of  claim 1 , wherein the light guide plates in at least one of the first and second light guide plate arrays have minute intaglio or embossed patterns which are formed on at least one of upper and lower surfaces, and the more minute intaglio or embossed patterns are far from the first or the second light array, the more minute intaglio or embossed patterns are formed in dense. 
     
     
       5. The backlight unit of  claim 1 , wherein each of the first and second light guide plates has a flat plate shape. 
     
     
       6. The backlight unit of  claim 1 , wherein each of the first light guide plates has a flat plate shape, and each of the second light guide plates has a wedge plate shape of which lower surface is inclined. 
     
     
       7. A liquid crystal display comprising:
 a liquid crystal display panel; and 
 a backlight unit that illuminates light to the liquid crystal display panel, 
 wherein the backlight unit includes a first light guide plate array including a plurality of first light guide plates arranged in parallel in a first direction to define a plurality of first light guide channels, a second light guide plate array including a plurality of second light guide plates arranged in parallel in a second direction intersected with the first direction to define a plurality of second light guide channels, the second light guide plate array being disposed under the first light guide plate array, wherein the first light guide plate array and the second light guide plate array define a matrix of blocks such that a luminance of each block is the sum of the luminance of the first and second light guide channels at each block; 
 a first light array arranged near at least one end of the first light guide plate array to illuminate light to the at least one end of the first light guide plate array, a second light array arranged near at least one end of the second light guide plate array to illuminate light to the at least one end of the second light guide plate array, 
 a first light array driving part independently controlling an amount of emitting light of each light source in the first light array and adjusting the current supplied to a light source of the first light array depending on a local dimming signal supplied directly from a picture analyzing part, and 
 a second array driving part independently controlling an amount of emitting light of each light source in the second light array and adjusting the current supplied to a light source of the second light array depending on a local dimming signal supplied directly from the picture analyzing part, wherein the picture analyzing part generates the local dimming signal for adjusting the current supplied to the first and second light arrays with reference to the luminance analyzed for each block to control the first and second light array driving parts, 
 wherein the first light array driving part is disposed along the first light array and the second light array driving part is disposed along the second light array, the first light array driving part not directly connected to the second light array driving part, 
 wherein a long edge of the first light guide plate extends beyond or is shorter than a long edge of the second light guide plate in a first direction along a plane of the first and second light guide plates, 
 wherein a short edge of the second light guide plate extends beyond or is shorter than a short edge of the first light guide plate in a second direction along the plane of the first and second light guide plates, the first and second directions being perpendicular to each other. 
 
     
     
       8. The liquid crystal display of  claim 7 , wherein surface light illuminated from the first and the second light guide plates is divided into a plurality of blocks having a matrix shape by the intersection of the first light guide light channels and the second light guide light channel. 
     
     
       9. The liquid crystal display of  claim 7 , wherein the first light array includes a plurality of first light sources arranged to correspond to the one ends of the plurality of first light guide plates, and a plurality of second light sources arranged to correspond to the other ends of the first light guide plates, and
 the second light array includes a plurality of third light sources arranged to correspond to the one ends of the plurality of second light guide plates, and a plurality of fourth light sources arranged to correspond to the other ends of the second light guide plates. 
 
     
     
       10. The liquid crystal display of  claim 7 , wherein the light guide plates in at least one of the first and second light guide plate arrays have minute intaglio or embossed patterns which are formed on at least one of upper surfaces, lower surfaces, and the more minute intaglio or embossed patterns are far from the first or the second light array, the more minute intaglio or embossed patterns are formed in dense. 
     
     
       11. The liquid crystal display of  claim 7 , wherein each of the first and second light guide plates has a flat plate shape. 
     
     
       12. The liquid crystal display of  claim 7 , wherein each of the first light guide plates has a flat plate shape, and each of the second light guide plates has a wedge plate shape of which lower surface is inclined.